1. Field of the Invention
This invention relates to optical systems, and more, particularly, to optical systems for imaging panoramic scenes onto flat focal planes.
2. Description of the Related Art
Existing wide field sensors do not combine an efficient optical system providing a large numerical aperture, a panoramic format with azimuth capability to 360 degrees and elevation coverage both above and below the horizon, with a focal plane format capable of supporting a single square or rectangular focal plane. Fish eye lenses and their derivatives have grossly distorted pupils as the field angle increases. The larger field angles of the fish eye lenses can have a pupil providing less than ten percent of the pupil area of the central system. This yields significant distortion and reduction in sensitivity. The resultant systems providing similar performance are thus relatively large and costly.
U.S. Pat. No. 4,994,670, issued to M. Noble et al, describes a dither scanned, multiple aperture panoramic sensor.
Canadian Patent No. 878,162, issued to D. Rees, describes a panoramic viewing system using a television system.
U.S. Pat. No. 4,395,093, issued to G. Rosendahl et al., describes a pair of hyperbolic reflective surfaces, which are used to image onto a complex arrangement of refractive elements to perform color correction and field corrections.
U.S. Pat. No. 4,012,126, issued to G. Rosendahl et al., discloses a panoramic optical system with a pair of hyperbolic reflective surfaces, which are used to image onto a complex arrangement of refractive elements to perform color corrections and field corrections.
U.S. Pat. No. 3,203,328, issued to H. Brueggemann, discloses a device in which the optical path includes a hyperbolic surface followed by a spherical surface. The focal plane configuration necessitated by this optical path requires an annular focal plane. The energy traveling from the primary to the spherical secondary optics passes through the center of the focal plane. This prevents the concept from being used with conventional focal planes.
U.S. Pat. No. 3,781,559, issued to E. Cooper et al., discloses a procedure for scanning a field with various fields of view.
U.S. Pat. No. 3,283,653, issued to A. R. Tokarzewski, discloses an all refractive design with many complex annular lens shapes, including conical sections.
U.S. Pat. No. 2,638,033, issued to D. R. Buchele, describes a refractive concept in which light rays pass across the prime axis of the initial optics. The invention has an exit pupil. There is only one significant optically powered surface for producing the image.
U.S. Pat. No. 3,552,820, issued to H. Brachvogel, describes a refractive first element set, which then directs energy to a re-imaging group.
U.S. Pat. No. 1,797,867, issued to J. C. Karnes discloses panoramic or omniscope optics, which includes, as the first element, a convex/concave element. This approach has significant problems producing a resolved image and pupil. The implementation of a focal plane region is a dispersed toroidal section which does not support an economical focal plane arrangement.
U.S. Pat. No. 2,244,235, issued to W. A. Ayres, describes a reflective spherical first element. This approach results in unacceptable distortion. The higher angles of elevation are very foreshortened on the focal plane, while the lower angles of elevation are severely limited in azimuthal resolution.
U.S. Pat. Nos. 2,923,220 and 3,151,524, issued to A. Bouwers, disclose inventions having wide angle camera lenses.
U.S. Pat. No. 3,514,186, issued to E. F. Poncelet, has deficiencies that are similar to that of the W. A. Ayres (U.S. Pat. No. 2,244,235) invention. Poncelet's first element is a sphere with the image refracted through it. Ayres' first element, on the other hand, is a reflecting sphere.
U.S. Pat. No. 3,894,798, issued to J. Wolfe, discloses a scanning invention.
U.S. Pat. No. 3,998,532, issued to W. Dykes, discloses a projection device for use with film.
U.S. Pat. No. 4,566,763, issued to P. Greguss, discloses an imaging block similar to that of Buchele (U.S. Pat. No. 2,638,033).
U.S. Pat. No. 5,402,168, issued to J. Fouilloy, discloses a camera concept which entails an optomechanical projector and scanning system.
U.S. Pat. No. 3,977,793, issued to P. Trotta, ,discloses a scanning radiation energy receiver.
Japanese Patent No. 63-172209, issued to Y. Tamagawa, describes a procedure for limiting the off axis radiation to an infra red detector.
U.S. Pat. No. 4,446,372, issued to M. Curnee, discloses a detector cold shield.